Passenger aircraft, buses, trains, and the like include passenger seats that must be both safe and cost-effective. In order to improve the cost effectiveness of such passenger seats, the materials used to manufacture these seats have become increasingly lighter in recent years. In particular, the use of lightweight materials in passenger seats is playing an increased role to continue the reduction in seat weight. While reducing the weight of passenger seats is an economic benefit, these passenger seats must still be capable of meeting the necessary safety and performance standards associated with passenger seats for use in passenger vehicles.
With respect to aircraft passenger seats, these seats are required to withstand forces that may be applied during a minor crash landing. During these types of events, the vehicle floor may become distorted. This distortion may cause the seat tracks to move out of plane, which creates high stresses on traditional passenger seat frames due to torsion instability of the seat.
To determine whether a passenger seat can withstand these types of forces, the seat must pass a series of performance tests, commonly referred to as “16g tests.” One criteria to determine whether an aircraft passenger seat has passed the 16g test is whether the seat remains attached to the airframe after the specified force has been applied. Moreover, new rigid seat designs must pass a pitch operation and a roll operation that occur prior to the 16g structural test.
Traditionally, passenger seat design have either been rigid in nature or have focused on incorporating energy absorbing features, such as energy absorption devices or plastic deformation, to relieve floor loads during the dynamic test event. These types of devices are not necessarily configured to also address the additional pre-test conditions.
With the advent of composite materials for construction of passenger seats, the ability to incorporate the necessary energy absorbing features into the passenger seats has become more challenging because these materials commonly have very small differences between tensile, yield, and rapture.
Accordingly, it may be desirable to provide a seat structure that provides the necessary energy absorption features for use with lighter weight materials. It may also be desirable to provide a seat structure that reduces stress due to floor distortion prior to application of a dynamic test.